The present invention relates to the construction of a mouse or trackball used with computer systems.
A keyboard is normally used to enter data manually into a computer system. These keyboards can be made in many different versions. However, they are all designed around the same basic concept: the keyboard contains groups of "keys", each assigned to a specific letter or number, or one or more signs. Additionally, most modern keyboards for data systems also contain series of function keys. Each function key may activate a special operation, depending upon the program being executed in the computer.
To simplify operations, many data systems and computer programs are also designed to work with a "Mouse" or "Trackball" in addition to the keyboard. Although these devices may take on many different forms, their basic functions are the same: a unit containing a rolling ball and one or more keys which may be pressed down.
The basic mouse design generally shown at 10 in FIG. 1 contains a mouse housing 11 with the ball 12 mounted at the bottom-side. A circular collar-like edge 8 can prevent the ball from falling out of the housing. Moving the mouse by rolling the mouse housing along a table 13 will make the ball roll and lift the ball free of the edge 8. This rolling ball operation is transferred to a corresponding movement of the cursor on the data screen of the connected computer. The ball operation can be translated into a distance and direction moved along an x-axis and a distance and direction moved along a y-axis. This movement is then transferred to the computer which moves the cursor on the screen in directions and distance corresponding to those given by the mouse movement. In most programs the relationship between a given rolling distance of the mouse ball and the corresponding movement of the cursor can be programmed, and also the acceleration of the mouse operation.
The basic trackball design shown generally at 14 in FIG. 2 differs from the basic mouse design since the ball 15 is on the top of the housing 16. The operation is performed by having the trackball housing 16 fixed (not moving), typically on a flat surface 17, while the operator rolls the ball 15 by hand. This again will correspond to a movement of the cursor as described above. A circular shoulder 9 can provide a seating surface for the ball or inner support rollers can support the ball.
Today, the word "mouse" is often used for both types and for simplicity, hereafter the term "mouse" will be used, regardless of whether it is a trackball or a traditional mouse design.
Either design controls the cursor on the computer screen in the same way, the differences between the designs being related to the movement of the ball. Both versions typically have one or more keys that the operator may activate, in addition to the operation of the ball. Depending upon the computer program, the movement of the ball together with the pressing of one or more keys will create specified operations or reactions by the computer program.
It is necessary to include in the mouse design a system that can detect the rolling movement of the ball and transfer it into some form of digital signals that can be used by the computer.
When the ball on a mouse is moving, the ball movement is transferred to an "x-" and a "y-" control system mounted internally in the mouse housing. Although this control system may vary in design, the basic principle is to register the movement of the ball relative to x and y axes. As shown in FIG. 3, typically the ball is touching three (or four) rollers 18, 19, and 20, where one (or two) is free-rolling as shown at 20 and the other two rollers 18 and 19 are connected to systems for detecting the direction of the revolution of the roller, the length of rolling, and also the speed. One of these detection rollers referenced 18 is referred to as the x-axis controller, and the other one referenced 19 (90 degrees off the x-axis roller) is referred to as the y-axis controller. These two rollers 18 and 19 work independently. Each detection roller is coupled to a movement sensor 21 or 22, which is an electromechanical device to sense the direction and speed of the roller movement.
FIGS. 4A, 4B show at 23 one method for implementing such a detection system. A disk 24, with a series of small holes 25, is mounted on the roller axle 26. A photo detection system 27 formed of a light transmitter 27A and a light receiver 27B senses each hole 25 as the disk 24 spins. With a proper design of the hole pattern, an electronic unit 28 can be designed to detect both the speed of the roller rotation, the direction, and the length. The information about the direction and movement from both the x- and y-controllers are transferred to the cursor on the data screen on the connected data system. Most programs allow the ratio between the movement of the ball in the x- and the y-direction and the corresponding movement of the cursor in the same directions to be set to suit the specific taste and requirements of the operator.
FIGS. 4A, 4B show one method for detection of the movement of the x- and y-rollers. Several other methods have been used. However, all these are based upon some sort of electromechanical system mounted upon the roller axles.
A major problem with this method where the rolling movement of the ball is mechanically transferred to two rollers (x and y), is that over time the interconnection between the ball and the two rollers itself may become less reliable. Very often this is due to dirt accumulating either on the ball or on the rollers. This will very often give an unreliable connection between the ball and the rollers, leading to incorrect cursor movements on the screen.
Due to this problem, several systems have been designed to overcome this by removing the rolling ball from the mouse design. One method replaces the ball with a disk 28 with pressure sensitive sensors 29 underneath. See FIG. 5. The operator presses on the disk 28 and the sensors 29 underneath detect where the pressure is on the disk and how hard it is, and converts that information into electrical signals to control the cursor.
Another method as shown in FIG. 6 is to replace the ball with a small pin or stick 30. See FIGS. 6A, 6B. Springs 31 keep the stick 30 normally in a vertical position. However, the operator can press the stick 30 away from this vertical position. Special sensors 32 are mounted at the bottom of the stick 30 and can detect in which direction the operator is pressing and how hard he is pressing. This information is then used to control the cursor.
Another method has been to replace the ball with two sets of small light transmitter/receivers 33A, 33B and 34A, 34B mounted at the bottom of a housing 35 at a 90 degree angle to each other. See FIGS. 7A, 7B. The mouse must be used in conjunction with a special pad 36. This pad 36 is reflective, except for a series of non-reflective lines 37A, 37B at a 90 degree angle on the surface of the pad. When the operator moves the mouse across the pads, both transmitter/receivers send out a light signal which is reflected back from the pad, unless the light beam happens to hit one of the non-reflective lines. Therefore, the two transmitter/receivers (x- and y-) will be interrupted for every line they pass. This can then be used to control the cursor operation.
Regardless of these methods, many customers still prefer to use a mouse with a rolling ball because it gives the operator a very good "control feeling". However, the problem of dust accumulating on the x- and y-rollers and the ball are forcing many users to switch to other, less dust sensitive designs.